How can Java be used to invoke a printer?

One can use Java to call a printer using the Java printing API. Below is a simple example code:

import java.awt.print.*;

public class PrinterTest {

    public static void main(String[] args) {
        // 获取默认的打印机
        PrinterJob printerJob = PrinterJob.getPrinterJob();

        // 创建一个打印任务
        Printable printable = new Printable() {
            @Override
            public int print(Graphics graphics, PageFormat pageFormat, int pageIndex) throws PrinterException {
                if (pageIndex > 0) {
                    return NO_SUCH_PAGE;
                }

                // 在这里编写需要打印的内容
                graphics.drawString("Hello, World!", 100, 100);

                return PAGE_EXISTS;
            }
        };

        // 设置打印任务
        printerJob.setPrintable(printable);

        // 打开打印对话框
        if (printerJob.printDialog()) {
            try {
                // 开始打印
                printerJob.print();
            } catch (PrinterException e) {
                e.printStackTrace();
            }
        }
    }
}

In this example, we first get the default printer, then create a print job, and define the printing content by implementing the Printable interface. In the print method, we can use the Graphics object to draw the content that needs to be printed.

Next, we set the print job to the PrinterJob object, open the print dialog using the printDialog method, where the user can select the printer and print options. Finally, we call the print method to start printing.

Please note that the availability of the printer and the correct installation of the printer drivers are necessary before running this code.